Self-reversing top

ABSTRACT

A self-reversing top is provided which, when spun in one direction, will rotate first in that direction and then will reverse its direction of rotation. The top is of integrated rigid construction having a curved lower contact surface the direction of least curvature of which is angularly offset from the principal axis of inertia.

United States Patent inventors App]. No.

Filed Patented Assignee Herbert F. Rondeau Winchester;

William Clark Goodchild, J r., Beverly; Hans Frederick Schaeier, Jr., Rockport, all of, Mass.

Apr. 11, 1969 July 27. 1971 Clearfloat, lnc.

Attleboro, Mass.

SELF-REVERSING TOP 6 Claims, 11 Drawing Figs.

U.S. CI

Int. Cl

[50] Field of Search [56] References Cited UNITED STATES PATENTS 2,237,463 4/1941 Trollen 46/47 X 2,700.246 1/1955 Ostberg 46/64 Primary ExaminerF. Barry Shay Assistant ExaminerRobert F. Cutting Attorney-Morse, Altman & Oates ABSTRACT: A self-reversing top is provided which, when spun in one direction, will rotate first in that direction and then will reverse its direction of rotation. The top is of integrated rigid construction having a curved lower contact surface the direction of least curvature of which is angularly offset from the principal axis ofinertiar PATENTEU Mama 3, 594' 944 SHEET 1 [IF 2 INVENTORS HERBERT E RONDEAU WILLIAM CLARK GOODCHILDHJR.

HANS FREDERICK SCHAEFERHJR BYW4M. 01 0 5 ATTORNEYS PATENTED JUL2 7 I97! SHEEI 2 OF 2 FIG. 6

FIG. 5

FIG?

FIG. 8

FIG. II

FIG.9

INVENTORS HERBERT F. RONDEAU WILLIAM CLARK GOOUCHILD, JR. HANS FREDRICK SGHAEFER JR.

7%, ZTM. 25

ATTORNEYS SELF-REVERSING TOP BACKGROUND OF THE INVENTION 1. Field of the lnvention This invention relates generally to tops and more particularly is directed towards a top of rigid, integrated construction having no moving parts and adapted to reverse its direction'of rotation when spun.

2. History of the Prior Art Dynamical tops having self-reversing characteristics have been mentioned in the art but are in the nature of experimental devices having no commercial value and not suited for mass production. Accordingly, it is an object of-the present invention to provide a self-reversing top of unique construction and configuration wherein the dissymmetry characteristic of the top is substantially concealed without impairment of its operation. Another object of this invention is to provide a selfreversing top of simple construction and one which is useful as a toy, paperweighL'advertising product or the like.

SUMMARY OF THE INVENTION This invention features a self-reversing top comprising an integrated body of rigid or substantially rigid construction having a principal axis about which the moment of inertia of the top will be at a minimum. The top is formed with a compound curved bottom surface on which the top is rotated. The bottom surface has a direction or a line of least curvature which is angularly offset from the principal axis ofinertia such that when the top is rotated it will spin first in the direction of the starting rotation and then reverse itself. The angular offset between the principal axis of inertia and line of least curvature is substantially concealed by various techniques. The top is useful as a toy, advertising device, paperweight or the ike. When used as an advertising device, it may be fabricated from transparent plastic and imbedded with various advertising materials. BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a top plan view of a self-reversing top made according to the invention,

FIG. 2 is a bottom plan view thereof,

FIG. 3 is an end elevation thereof,

FIG. 4 is a side elevation thereof,

FIGS. 5, 6 and 7 are cross-sectional views taken along the lines 5-5, 6-6 and 7-7, respectively, of FIG. 4,

FIGS. 8, 9, 10 and II are views in perspective illustrating operation of the top.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIGS. 1 through 7, there is illustrated one preferred form of the invention. In this embodiment a top 10 is of integrated construction molded or otherwise formed from a rigid or semirigid material such as plastic. Clear acrylic plastic is found to be particularly satisfactory since it lends itself to?" casting insuitable molds and hardens into a hard, durable product having a smooth finish and one which may be formed with one or more selected embedments 12 which embedment may be an advertisement device, decoration or the like. In any event the top I0 of the illustrated embodiment is of elongated construction, the particular top shown being 5% inches in overall length, W4 inches in width and approximately I% inches in overall height. These dimensions are only by way of illustration and the top may be fabricated in a wide variety of sizes as well as in different shapes. In the illustrated embodiment, the upper surface of the top is flat while the bottom surface thereof is curved in the form of a flattened ellipse. The bottom surface serves as the contact surface for the top on which the top is rotated against a smooth, flat surface such as a tabletop, floor or the like.

The distribution of the mass of the top relative to its center of gravity is important to the self-reversing characteristics of the top. The top will have one axis 14 about which the momerit of inertia of the top 10 will be at a minimum. This axis will be a principal axis of inertia and will align or nearly align with the longest dimension of the top. For purposes of illustration the principal axis of inertia 14 is shown as aligning with the longest dimension of the top 10.

Over the bottom surface of the top and through a point of contact 16 with a table surface 17, or the like, there will be a direction or line of least curvature indicated by reference character 18 and extending generally lengthwise of the top but slightly diagonal thereof so as to form a small angle 20, as viewed from above or below, with the axis of minimum inertia 14. The magnitude of the angle 20 does notappear to be critical but 4 has been found to work satisfactorily and an angle range of 28 appears to provide the bestaction. The radius of curvature along the line of least curvature 18 is on the order of l2 inches in the illustrated embodiment. The radius of curvature along the line of greatest curvature is on the order of 1% inches. Here again these dimensions are only by way ofexample and may be altered according to particular sizes and configurations.

The axis of minimum inertia 14 may be displaced clockwise or counterclockwise from the line ofleast curvature 18. If the axis of minimum inertia I4 is displaced clockwise from the line of least curvature 18, the top will spin smoothly in the clockwise direction if given an initial spin in the clockwise direction. On the other hand, if the top is first spun in a counterclockwise direction, it will make several revolutions in the counterclockwise direction, will undergo unstable rocking oscillations, will stop its counterclockwise rotation and will reverse its direction to turn smoothly in a clockwise direction. If the axis of minimum-inertia is displaced counterclockwise from the line of least curvature then thetop will operate in a reverse manner, namely it will spin smoothly in a counterclockwise direction or if started clockwise will reverse itself to spin in the counterclockwise direction.

In FIGS. 8 through 11 there is illustrated a series of views showing the top in operation. In FIG. 8 the top 10 is held in the hand and placed on a table or other suitable smooth, flat surface and spun in a clockwise direction. The top will spin by itself as shown in FIG. 9 but very rapidly will develop rocking oscillations as suggested in FIG. 10. The spinning of the top in the clockwise direction will then stop and the top, of itself, will reverse its direction to spin smoothly in the counterclockwise direction as suggested in FIG. I].

The operation of the top depends on the contour of the contact surface and it should be true and fair and free from dents or other local imperfections. The top should be fabricated from a material which is rigid and avoid any loose components which would dissipate energy and deaden the action of the top. If the top includes appendages such as the embedment 12 it also should be rigid, otherwise undesired vibrations may develop and upset the proper operation of the top. Tops may be solid or hollow with no important effect on their behavior except that a moderate weight is desirable to store the input energy and prolong the spinning action. It is useful to note that tops of identical dimensions but of different materials would behave the same i.e. a lead top would act like a plastic top except only that its motion would last longer. Larger tops among geometrically similar tops will be slower in their vibrations but their motions will last longer.

The angular offset between the axes of shape and mass normally will produce a dissymmetry of twisted appearance in the top which may be visibly apparent. This distorted appearance may be concealed or minimized so as to add mystery to the action of the top and also to provide a more symmetrical-appearing and more readily manufactured product.

One means of obtaining this concealment is to create voids or introduce metal inserts within a top made of opaque materi- On the other hand, if the material of the top must be of uniform density throughout then a more complex shape 'is required. In this case it is useful to observe that the point of contact 16 of the top on the table or other surface remaihs within a limited area while the top is in motion. Portions of the bottom surface of the top which are outside of this contact area, may be faired or altered as in the illustrated embodiment to avoid a twisted appearance.

While the top has been illustrated in an oblong configuration, it may also be fabricated in other shapes such. for example, square shape, circular or otherwise,-all of which shapes will display the self-reversing characteristics as long as there is an angular displacement between the line of least curvature and the axis of the minimum inertia. In all configurations dissymmetry may be minimized or obscured by contouring the top to form smoothly faired lines such as to conceal the dissymmetry or by embedding weights at suitable locations within the body so as to displace the axis of principal inertia from the line of least curvature.

The characteristics of the top may be altered by providing weights in the top that can be adjusted as to position for changing the principal axis of inertia with respect to the direction of least curvature. By shifting the weights it ispossible to reverse the reversing action. The top may thus be made naturally rightor left-handed depending upon the position of the reversing weights.

Having thus described the invention what we claim and desire to obtain by Letters Patent of the United States is:

l. A self-reversing top, comprising a. an integrated elongated body of rigid material,

b. said body being formed with a bottom contact surface smoothly curved substantially from end-to-end and on which said top may rest and be rotated,

c. said bottom surface being'formed in a compound outwardly contoured curve wherein the curvature in one direction is less than the curvature in another direction,

d. the mass of said body being distributed in such a manner that its principal axis of inertia is angularly offset from the direction of least curvature of said bottom surface whereby said top when spun in one direction on a smooth horizontal surface will reverse itself and spin in an opposite direction.

2. A self-reversing top according to claim 1 wherein said principal axis of inertia and said direction of least curvature are angularly offset by approximately 2 to 8.

3. A self-reversing top according to claim 1 wherein said body at least in part is of transparent material.

4. A self-reversing top according to claim 3 including an embedment within said transparent material.

5. A self-reversing top according to claim 1 including weights disposed in said body in position to selectively displace the principal axis of inertia from the direction of least curvature.

6. A self-reversing top according to claim 5 including means for moving said weights to different fixed positions. 

1. A self-reversing top, comprising a. an integrated elongated body of rigid material, b. said body being formed with a bottom contact surface smoothly curved substantially from end-to-end and on which said top may rest and be rotated, c. said bottom surface being formed in a compound outwardly contoured curve wherein the curvature in one direction is less than the curvature in another direction, d. the mass of said body being distributed in such a manner that its principal axis of inertia is angularly offset from the direction of least curvature of said bottom surface whereby said top when spun in one direction on a smooth horizontal surface will reverse itself and spin in an opposite direction.
 2. A self-reversing top according to claim 1 wherein said principal axis of inertia and said direction of least curvature are angularly offset by approximately 2* to 8*.
 3. A self-reversing top according to claim 1 wherein said body at least in part is of transparent material.
 4. A self-reversing top according to claim 3 including an embedment within said transparent material.
 5. A self-reversing top according to claim 1 including weights disposed in said body in position to selectively displace the principal axis of inertia from the direction of least curvature.
 6. A self-reversing top according to claim 5 including means foR moving said weights to different fixed positions. 